1. Field of the Invention
The present invention relates to a carburetor, and more especially to a carburetor for locomotives with a cam assembly and a vacuum horsepower adjustment valve, which is more efficient, saves fuel and reduces pollution.
2. Description of the Prior Art
The design of carburetors is important to improving the performance of locomotives. When consumers purchase locomotives, besides the speed of the locomotive, fuel efficiency and environmental protection are important factors which need to be considered. So before locomotives sold out, most of them need to have their idle-speed oil passage adjusted to minimize the amount of gas (such as HC, NOx, CO etc.) for obtaining the optimal fuel saving point, thereby achieving a state in which gas exhaust reach their lowest and fuel use is minimized.
Taiwan Patent No. 398577, published on Jul. 11, 2000, provides an automatically adjustable carburetor which reduces fuel consumption and pollution. The carburetor has an automatically adjustable choke device in an air inlet path. The choke device is disposed in front of a throttle valve with an oil injection needle in the air inlet path. The choke device includes a fixing axle, an air inlet annular base, a pair of clip springs, a choke cone, and a spring. The choke cone controls the air draw into the carburetor, so as to improve the performance of the carburetor and gas exhaust.
However, a main oil path of the above automatically adjustable carburetor which reduces fuel consumption and pollution uses an oiling line to drive a throttle. When the locomotive moves at high speeds, due to the cone design of the oil injection needle, a gap between the oil injection needle and an emulsifying pipe becomes larger following the movement of the oiling line so that the overflowed fuel particles is difficult to atomize and fuel cannot burn sufficiently, thereby causing more pollution. Furthermore, when the choke cone runs under vacuum suction from the engine, the precise location of the choke cone cannot be controlled effectively, thereby the amount of air input cannot be controlled well and the mixture of the fuel and air is unstable.
Hence, the inventors of the present invention believe that the shortcomings described above are able to be improved and suggest the present invention which is of a reasonable design and is an effective improvement based on deep research and thought.